Absorption refrigeration, chilling, heat pump, and related apparatus employing a composite refrigerant and a single refrigeration loop is well known. The refrigeration loop includes a generator, a condenser, an evaporator, and an absorber. A variety of composite refrigerant systems can be used is in such apparatus. Two examples are an ammonia/water system and a lithium bromide/water system.
Heat from an external source of energy is added to the composite refrigerant in the generator. The generator heats the composite liquid refrigerant sufficiently to distill out a vapor of the more volatile component or phase of the refrigerant (for example, ammonia vapor in the case of the ammonia/water refrigerant and water in the case of the lithium bromide/water system), leaving a less-volatile component or phase of the refrigerant behind. The less-volatile refrigerant component can either be more concentrated than the composite refrigerant (as when water vapor is distilled out of an aqueous lithium bromide solution) or more dilute than the initial refrigerant (as when ammonia is driven out of water solution). The remaining less-volatile refrigerant component is removed to the absorber.
The condenser receives the vapor phase of the refrigerant from the generator and condenses it to liquid form (also known as a condensate). The heat released by the condensation of the vapor is rejected to a cooling tower, cooling water, some other external heat sink, or another stage of the refrigeration apparatus.
The evaporator withdraws heat from a heat load (i.e. the building air, refrigerator contents, cooling water, or other medium the system is designed to cool) by evaporating the condensed liquid refrigerant in direct or indirect contact with the heat load. The evaporator thus re-vaporizes the volatile refrigerant component.
The absorber contacts the refrigerant vapor component leaving the evaporator with the less-volatile refrigerant component leaving the generator. The contacting process generates heat when the vapor phase is reabsorbed into the less-volatile refrigerant phase. This heat is rejected to a cooling tower, cooling water, another stage of the refrigeration apparatus, or some other heat sink. The original composite refrigerant is re-formed in the absorber, and then is returned to the generator to complete the cycle.
Triple-effect refrigeration apparatus has two separate but interacting refrigeration circuits of the type described above (sometimes respectively known as a high-temperature loop and a low-temperature loop, as a high loop and a low loop, or as a first loop and a second loop). The first and second loops are interconnected so heat is transferred from the absorber and the condenser of the first loop to the generator of the second loop. Both the first loop and the second loop accept heat from the heat load. The second loop rejects heat from its absorber and its condenser to an external heat sink.
In one version of triple-effect apparatus, the first-loop condenser is a coiled pipe disposed within the second-loop generator vessel. In the same apparatus, heat from the first-loop absorber in one vessel is transferred indirectly to the second-loop generator in another vessel. The indirect heat transfer is accomplished via a heat-exchange fluid circulated alternately through a first heat exchanger in the first-loop absorber and a second heat exchanger in the low-temperature generator vessel. The use of separate heat exchangers for the first-loop absorber and the second-loop generator introduces inefficiencies and adds to the cost, complexity, and waste heat generation of the apparatus.
One known generator, which uses steam as a heat source, comprises an outer vessel which is closed at each end and inner vessels which are vertical tubes passing through the outer vessel. Heat supplied to the outer vessel in the form of steam from a source outside the refrigerant loop heats the tubes, and thus the refrigerant within the tubes. The refrigerant is boiled within the tubes, and the vapor and entrained liquid is conveyed upwardly and expelled from the upper ends of the tubes.
An absorber is known in which the less-volatile component of the refrigerant trickles down from coil to coil on the substantially horizontal coils of a heat exchanger as it absorbs the refrigerant vapor leaving the evaporator. The heat exchanger removes the heat resulting from the absorption process. The heat is rejected to a heat sink, such as cooling water.
Accordingly, an object of the present invention is to provide plural-loop absorption refrigeration apparatus which has less operative parts than previous systems.
Another object of the invention is to provide absorption refrigeration apparatus which is more efficient than prior apparatus.
An additional object of the invention is to provide absorption refrigeration apparatus which costs less, weighs less, takes up less space, and wastes less heat than prior apparatus.
Yet another object of the invention is to reduce or eliminate the need to transfer heat from one place to another within plural-loop absorption refrigeration apparatus, apart from transfers inherent in a single refrigeration cycle.
Still another object of the invention is to combine the generator of a lower refrigeration loop, and the absorber of a higher refrigeration loop in one outer vessel.
Other objects of the invention will become evident to one of ordinary skill in the art from consideration of the present disclosure.